Heavy-duty wipe and method for producing same

ABSTRACT

AN IMPROVED HEAVY-DUTY WIPE MADE OF NON-WOVEN MATERIALS, AND A METHOD OF PRODUCING THE SAME. THE WIPE INCLUDES A CENTRAL LAYER OF MULTI-PLY CELLULOSIC TISSUE, A WEB OR SHEET OF OPEN-MESH NON-WOVEN CROSSED THREADS ON EACH SIDE OF THE CENTRAL LAYER, AND A THIN APPLIQUE OF FINE FIBROUS MATERIAL BONDED TO THE OUTER SURFACE OF EACH CROSSED-THREAD WEB. THE CENTRAL LAYER OF MULTI-PLY CELLULOSIC TISSUE IS BONDED TO BOTH THE WARP THREADS AND FILL THREADS ON THE WARP THREAD SIDE OF EACH OF THE TWO WEBS OF NON-WOVEN MATERIAL, AND THE FIBROUS APPLIQUES ARE BONDED TO THE FILL THREAD SIDES OF EACH WEB.

Jan. 9, 1973 G. n. THOMAS 3,709,764

HEAVY-DUTY wIPE AND METHOD FOR PRODUCING SAME Original Filed Dec. 23.1968 fa waff/fm Jeff/7m@ ,sf fam/1v@ United States Patent O 3,709,764HEAVY-DUTY WIPE AND METHOD FOR PRODUCING SAME Gordon D. Thomas, Neenah,Wis., assignor to Kimberly- Clark Corporation, Neenah, Wis.

Original application Dec. 23, 1968, Ser. No. 788,987,

now Patent No. 3,616,133. Divided and this application May 3, 1971, Ser.No. 139,823

Int. Cl. B32b 5/ 00 U.S. Cl. 156--177 9 Claims ABSTRACT OF THEDISCLOSURE An improved heavy-duty wipe made of non-woven materials, anda method of producing the same. The wipe includes a central layer ofmulti-ply cellulosic tissue, a web or sheet of open-mesh non-wovencrossed threads on each side of the central layer, and a thin appliqueof fine fibrous material bonded to the outer surface of eachcrossed-thread web. The central layer of multi-ply cellulosic tissue isbonded to both the warp threads and fill threads on the warp thread sideof each of the two webs of non-woven material, and the fibrous appliquesare bonded to the fill thread sides of each web.

This application is a divisional of my copending application Ser. No.788,987, led Dec. 23, 1968, now Pat. No. 3,616,133.

DESCRIPTION OF THE INVENTION The present invention relates generally toheavy-duty wipes and, more particularly, to an improved heavy-duty wipemade of non-woven materials, and a method of producing the same.

It is a primary object of the present invention to provide an improvedheavy-duty wipe having superior strength, abrasion resistance, andsoftness properties combined with adequate bulk and absorbency. A moreparticular object of the invention is to provide such an improvedheavy-duty wipe having improved resistance to grinning and thread pickoff, a desirable soft feel, and relatively high absorbency rate andcapacity.

Another object of the invention is to provide an improved heavy-dutywipe of the type described above which can be efficiently manufacturedat high production rates and at a relatively low cost.

A further object of the invention is to provide a method of producing animproved heavy-duty wipe of the foregoing type.

Other objects and advantages of the invention will become apparent fromthe following detailed description taken in connection with theaccompanying drawings, in which:

FIG. 1 is a schematic plan view of a heavy-duty wipe embodying theinvention, with sections of successive layers of the wipe materialremoved to reveal underlying layers;

FIG. 2 is a schematic side elevation of the heavy-duty wipe shown inFIG. 1 on an enlarged scale;

FIG. 3 is a schematic end elevation of the heavy-duty wipe shown in FIG.1 on an enlarged scale;

FIG. 4 is a schematic representation of a process for producing one halfof the heavy-duty wipe shown in FIGS. 1 through 3 in accordance with theinvention; and

FIG. 5 is a schematic representation of a process for laminating twolayers of material prepared by the process of FIG. 4 to produce theheavy-duty wipe shown in FIGS. 1 through 3 in accordance with theinvention.

While the invention is susceptible of various modifications andalternative forms, certain specific embodiments thereof have been shownby way of example in the drawings which will be described in detailherein. It should be 3,709,764 Patented Jan. 9, 1973 ICC understood,however, that it is not intended to limit the invention to theparticular forms disclosed but, on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention.

Referring now more particularly to the accompanying drawings, theinvention is embodied in a wipe represented in FIGS. 1 and 2, andincluding a flat central layer 10 of absorbent material formed of amultiplicity of plies 11 of creped cellulosic tissue, and layers 12 and13 of nonwoven fabric on the opposite faces of the flat central layer10. In order to provide a wipe with superior absorbency characteristics,the multi-ply tissue layer 10 in the illustrative embodiment comprisesfour plies of creped tissue having a stretch per ply of about 15 to 75%,preferably 25 to 30%, and a dry, uncreped basis weight of from about 4to about 13 pounds per 2,880 sq. ft., preferably about 7 to 8 pounds per2,880 sq. ft. In the particular embodiment illustrated, the two plies 11of cellulosic tissue adjacent each fabric layer 12 or 13 are bonded toeach other and to the adjacent fabric layer by means of adhesive that isoriginally applied to only the fabric layer, but it will be understoodthat a greater number of tissue plies may be used and interbonded byadhesive applied to a sufficient area of adjacent surfaces of themultiple plies to hold the plies together during use. In the lattercase, the adhesive will normally be applied in a discontinuous patternso that the desired interbonding is achieved with a minimum of adhesiveand without reducing the flexibility of the multi-ply layer 10. In anyevent, the particular adhesive employed should always be insoluble inoil and any other liquids that might be absorbed in the wipe during use.

As can b seen in FIGS. l and 2, each of the two layers 12 and 13 ofnon-woven fabric comprises a set of spaced warp threads 20 which extendin the longitudinal or machine direction, and a set of fill threads 21which extend across the warp threads in the transverse direction. Sincethe fabric is non-woven, the fill threads 21 are all on the same side ofthe warp threads 20, with the two sets of threads disposed inface-to-face relation to each other and adhesively bonded together wherethe threads of one set cross the threads of the other set. Non-wovenfabrics of this type are well known in the art, and may be made by anyof several different known methods and apparatus, one example of whichis described in U.S. Pat. No. 2,841,202 to H. W. Hirschy. The threads ineach of the two cross-laid sets normally run parallel to each other andare uniformly spaced, but the fabric may be formed with the threadsfollowing non-parallel or irregular patterns if desired, as long as oneset of threads is disposed entirely on one side of the other set. 1twill be understood that the term threads is intended to include bothmonofilament and multifilament structures, although multilamentstructures are generally preferred in non-woven fabrics.

It is critical in the present invention that the layers 12 and 13 ofnon-woven fabric have the warp threads 20, i.e., the machine directionthreads, on the inner surfaces thereof, and the fill threads 21, i.e.,the transverse threads, on the outer surfaces thereof. Because the warpthreads are the machine direction threads, they are inherently tensionedmore than the fill threads, which are the transverse direction threads.Consequently, when the non-woven fabric is disposed with the fillthreads 21 on the outer surface thereof, the ll threads tend to sagbetween the warp threads 20 (see FIG. 3) and make more effective contactwith the exposed portions of the central layer 10 of cellulosic tissuethan would be possible with the warp threads disposed on the outersurface. Similarly, the till threads 21 can be more effectively presseddown 3 between the warp threads 20 into intimate contact with thecentral layer of cellulosic tissue, by means of a calendering operationfor example. As a result, the final composite material is considerablyless susceptible to thread pick-off than a material having the warpthreads on the outside. This is an especially significant feature in aheavy-duty wipe, which is continually rubbed over rough surfaces andsharp corners which tend to pick or pull threads from the surface of thewipe during normal usage.

' It is also critical that both the warp threads 20 and the fill threads21 be coated with adhesive in the two layers 12 and 13 of non-wovenfabric. By applying adhesive to both the Warp and fill threads, thecentral layer 10 of cellulosic tissue is bonded to both sets of threadsso that the resulting composite material is not subject to grinning whenstressed in the transverse direction, i.e., the central layer 10 ofcellulosic tissue, cannot slide over one set of threads and rupture dueto the lack of an effective bond between the relatively strong threadsand the relatively Weak cellulosic tissue, as in the case when adhesiveis applied to only one set of threads.

In accordance with a further aspect of the invention, thin appliques 30and 31 of fine fibrous material are bonded to the outer surfaces of thelayers 12 and 13 of non-woven fabric on the opposite faces of thecentral layer 10 of cellulosic tissue. Thus, in the illustrativeembodiment, thin appliques 30 and 31 are applied to the outer surfacesof the two fabric layers 12 and 13, and the appliques are bonded to thefabric by means of the adhesive on both the warp and fill threads and21. The appliques and 31 are Well known per se in the art, and arepreferably made of ne fibers of cotton or other natural or syntheticfibers deposited on the fabric layers 12 and 13 in a random manner. Mostof the fibers engage and become bonded to one or more of the warp andfill threads of the fabric layers 12 and 13, but the fibers in theapplique also become intertwined so that a fiber which does not engage aWarp or fill thread is nevertheless anchored to the laminate via otherfibers which are directly attached to the fabric layers. The fibrousappliques 30 and 31 are preferably formed directly on the fabric layers12 and 13 before the fabric is laminated to the central layer 10 ofcellulosic tissue, but if desired the appliques can be formed on thefabric after the lamination of the fabric layers to the cellulosictissue, or the appliques may even be pre-formed and subsequentlylaminated to the non-woven fabric. 'If desired, relatively long fibers,such as 3winch cut rayon staple, may be used to insure that each fibercontacts at least one of the threads in the cross-laid fabric andthereby provide improved resistance to linting.

It has been found that the particular combination of materials embodiedin the composite laminate of FIGS. 1 and 2 is superbly suited for use asa heavy-duty wipe. Thus, the central layer 10 of cellulosic tissueprovides a relatively high absorbent capacity, and is readily accessible'Via the relatively large openings in the fabric layers 12 and 13 andthe thin fibrous appliques 30 and 31 so that the absorbency rate is alsorelatively high. The nonwoven fabric layers on the outer surfaces of thecellulosic tissue provide the composite laminate with the relativelyhigh tensile strength and abrasion resistance required in a heavy-dutywipe. In this connection, a relatively high thread count, e.g., 6 x 10or 12 x 5 (number of warp threads per inch by number of fill threads perinch), is preferred to provide good abrasion resistance, and a denier inthe range of about 30 to about 70 is preferred to provide adequatestrength characteristics. From a coststrength standpoint, acrossed-threadvfabric made of 40 denier high tenacity nylon isespecially preferred. Finally, the fibrous appliques 30 and 31 on theouter surfaces of the fabric layers provide the composite wipe withsoftness and enhance the absorbency of the wipe due to the relativelylarge pores in the appliques rapidly transporting absorbed liquids tothe smaller pores of the cellulosic tissue which retains the liquid. Therelatively small pore structure of the cellulosic tissue retainsabsorbed liquids under compression, While the relatively large poresstructure of the appliques provides a high absorbency rate and good oilfilm removal ability.

Several samples of the particular product illustrated in FIGS. 1-3, andmade with the exemplary materials described above, were subjected tophysical tests to determine the oil absorbency rate and the oil filmremoval characteristics. In the oil absorbency rate test, a 4-inchsquare specimen was placed on a wire screen, and 0.1 milliliter of whitemineral oil at about 73 F. was discharged onto the specimen near thecenter thereof. The oil was discharged from a syringe held at an angleof about 30 from horizontal, and with the tip of the syringe in theliquid, nearly touching the specimen. The time was measured from thestart of the liquid flow until the end point when the liquid wascompletely absorbed, as indicated by no further reflection of light fromit when viewed at an angle. The oil film removal test was conducted byplacing l milliliter of the same oil on a vitrolite (black glass)surface and spreading it out into a thin film Within about a 12" circle.The Wipe material was then used to remove the oil film, with the timebeing measured from the start of the wiping until the removal of theshine, or the development of a dull gloss. These tests were conducted onthe illustrative product both with and without the cotton applique onthe outer surfaces thereof, with the following results:

No applique Applique Property Oil rate (seconds) 6 3-4 Oil film removal(seconds) 6 4-6 Further physical tests conducted on the same sampledescribed above, with the cotton applique on the outer surfaces thereof,yielded the following results:

CD 1,817 1,400 Grams/1" wide and stretch 40 32 Basic weight #/MSF 24. 826. 5 Productl thickness (10-4 x 4) 0. 293 0. 290

In FIGS. 4v and 5, there is illustrated a preferred method of formingthe particular wipe shown in FIGS. l-3. Thus, turning first to FIG. 4, acontinuous fabric web 40 of open-mesh, non-woven crossed threads(corresponding to the layers 12 and 13 in the illustrative wipe of FIGS.1-3) is passed under a guide roll 41 to an adhesive application stationindicated generally 42. The station 42 includes a first pair of rolls42a for applying adhesive to the warp thread side of the web 40, and asecond pair of rolls 42b for applying adhesive to the fill thread side.The web 40 may be fed to the adhesive station 42 directly from theapparatus for making the crossed-thread fabric, or it may be unwoundfrom a supply roll of previously manufactured fabric. The illustrativeadhesive application station 42 includes two application rollers 42a and42b, one on each side of the web, to insure uniform application ofadhesive on both sides of the web. It can be seen that the applicators42a and 42b apply an adhesive coating to both sets of the cross-laidthreads, i.e., both the fill threads 20 and the warp threads 21.

While various adhesives may be employed, advantages reside in the use ofplastisols which, as is well known, are colloidal dispersions ofsynthetic resins in a suitable organic ester plasticizer. While manyadhesives of this nature are known, those found particularly useful forincorporation in the product of this invention include vinyl chloridepolymers, and copolymers of vinyl chloride with other vinyl resins,plasticized by organic phthalates, sebacates, or adipates. Thesecombinations provide a fast curing plastisol adhesive characterized byrelatively low viscosity, low migration tendencies, and minimumvolatility. Such adhesives remain soft and flexible after curing, can bereactivated by the application of heat and pressure, such as byhot-calendering, and insure that the resultant laminated product retainsthe desired softness, and proper hand and feel. Although plastisols arepreferred, polyvinyl resins per se, plasticized or unplasticized, suchas polyvinyl acetate, and copolymers may also be used. Other exibleadhesives may also be used, including acrylic resins such as the alkylacrylates, and butadiene resins such as butadiene-styrene and butadieneacrylonitriles.

From the applicator 42, the adhesive coated fabric web 40 is passedaround a pair of heated steel rolls 43a and 43b for the purpose ofcuring and solidifying the adhesive. When using the preferred plastisoladhesives described above, the heated rolls 43a and 43h are typicallymaintained at a temperature of about 200 to 300 F. which is sufficientto set the plastisol adhesive.

For the purpose of applying an applique 44 (corresponding to theappliques 30 and 31 in the illustrative wipe of FIGS. 1-3) to the fabricweb 40, the web is withdrawn from the heated roll 43b and passed underan air former 46 in a generally horizontal path. The air former 46applies fine fibers, which may be natural or synthetic, to the travelingfabric web 40 by means of an air blast, gravity feed, or similarmechanism. For example, the air former may apply 4.0 to 5.0 grams persq. yd. of fine fibers to the fabric web. As will be understood by thosefamiliar with this art, the fine fibers tend to lightly film or bridgeacross the openings between the crossed threads of the fabric web.

For reasons described previously, it is important that the fibrousapplique 44 be applied to the till thread side of the fabric web 40, andthus the web must be oriented so that the fill threads are on the uppersurface of the web 40 as it passes under the air former 46. After thefiber applique 44 has been applied to the fabric web 40, the web ispassed over a guide roll 48 where a multi-ply layer 49 of cellulosictissue (corresponding to half of the central layer in the illustrativewipe of IFIGS. 1-3) is unwound from a supply roll 50 and laminated tothe underside of the fabric web. As explained previously, it isimportant that the cellulosic tissue 49 be laminated to the warp threadside of the fabric web 40. In order to form the specific wipe shown inFIGS. 1-3, the layer 49 of cellulosic tissue contains two plies, i.e.,half the thickness of the ultimate central layer 10 in the final wipe.

In order to bond both the applique 44 and the tissue layer 49 to thefabric web 40, the laminate is passed around a heated steel roll 51, andthen through the nip formed by the heated roll 51 and a nylon calenderroll 52. The heat from the roll 51 reactivates the previously setadhesive on the fabric web 40', while the calendering operation pressesthe fill threads on the outer surface of the fabric web 40 down betweenthe warp threads on the inner surface, and into intimate engagement withthe tissue layer 49. When using the preferred plastisol adhesivesdescribed above, the steel roll 51 is heated to a temperature of about320 to 350 F., to complete the curing of the adhesive and firmly bondthe tissue layer 49 to the web 40. In order to prevent fiber pick-off onthe nylon calender roll 52, the roll 52 should contact the tissue sideof the web, while the metal roll 51 contacts the applique-fabric side ofthe web, as illustrated in FIG. 4.

From the calender roll 52, the bonded laminate is passed through aconventional hot microcreper 53 for the purpose of improving thesoftness and bulk of the wipe,

and also imparting stretch with minimal strength loss.

i in the creped product withdrawn from the microcreper 52, the crepedweb is passed around a pair of cooling rolls 54a and 54b. This coolingstep insures that any remaining tack in the adhesive is completelyeliminated so that the laminate can be readily handled and wound on astorage roll, and subsequently unwound therefrom Without sticking. Inthe illustrative process of lFIG. 4, the lam'nate is pin embossed bypassing it between a pin roll 55 and a brush roll S6 before winding iton the storage roll 57. The pin embossing, which again is carried outwith conventional equipment well known to those skilled in the art,further improves the absorbency and softness of the final product.

In order to complete the formation of the composite wipe shown in FIGS.1-3, two rolls 57a and 57b, both formed by the process illustrated inFIG. 4, are unwound and laminated as illustrated in FIG. 5. Thus, thelaminate from roll 57a is unwound over a guide roll 60 and passed intothe nip of a pair of calender rolls 61 and 62 with the cellulosic tissuelayer 49a on the underside thereof. The laminate from the other roll5711 is passed around a pair of guide rolls 63 and 64, through anadhesive applicator '65, and then into a low pressure nip formed byrolls 61 and 62 with the cellulosic tissue layer 49b on the upper sidethereof. The adhesive applied to the tissue side of the laminate fromthe roll 57b in the applicator 65, which is preferably a polyvinylacetate adhesive, bonds the two face-to-face cellulosic tissue layers49a and 49b together as the two laminates are pressed together by thecalender rolls 61 and 62, thereby forming a final composite laminate 66corresponding to the wipe shown in FIGS. 1-3. This laminate is thenpassed on to downstream equipment for performing the desired slitting,sheeting, and/ or folding operations. The adhesive pattern printed onthe tissue side of the laminate 49b by the adhesive applicator 65 ispreferably applied in a discontinuous pattern, such as in a dot patternby means of intaglio cell roll. As will be apparent to those skilled inthis art, such a discontinuous adhesive pattern firmly bonds the twotissue layers without adversely affecting the absorbency and exibilitythereof.

While the invention has been described above with specific reference tocertain particular embodiments, it will be understood that variousmodifications may be made within the spirit and scope of the invention.For example, the fine cotton appliques described above may be replacedby materials such as longer airlaid rayon fibers (approximately 0.75inch), a drawn web of rayon, or a carded web for improved lintingproperties. Another possible modification is to dispose the cottonapplique or other fibrous material between the warp thread side of thenon-woven fabric and the central layer of cellulosic tissue, again forimproved linting properties.

As can be seen from the foregoing detailed description, this inventionprovides an improved heavy-duty wipe having superior strength, abrasionresistance, and softness properties combined with adequate bulk andabsorbency. More particularly, the Wipe has improved resistance togrinning and thread pick-off, a desirable soft feel, and a relativelyhigh absorbency rate and capacity. Furthermore, the wipe can beefficiently manufactured at high production rates and at a relativelylow cost.

I claim as my invention:

1. A method of forming a laminated 'heavy-duty wipe comprising the stepsof providing a web of non-woven fabric made of open-mesh cross-laid andbonded threads, said fabric including spaced warp threads extending inthe machine direction on one side of said fabric and spaced fill threadsextending in the transverse direction on the other side of said fabric,said warp and `iill threads being coated with adhesive, laminating alayer of absorbent material formed of a multiplicity of plies of crepedcellulosic tissue to the warp thread side of said web of nonwoven fabricand bonding said absorbent material to both the warp and iill threads,and bonding two layers of the resulting laminate together with thetissue layers facing each other to form a composite laminate with saidtissue layers on the inside and said fabric webs on the outside.

2. A method of forming a laminated heavy-duty Wipe as set forth in claim1 wherein a thin applique of fine fibrous material is bonded to the lillthread side of said web of non-woven fabric.

3. A method of forming a laminated heavy-duty wipe as set forth in claim2 wherein said applique comprises randomly oriented fine cotton fibers.

4. A method of forming a laminated heavy-duty wipe as set forth in clam1 wherein said non-woven fabric has a thread count of at least tivethreads -per inch in one direction and at least ten threads per inch inthe other direction.

5. A method of forming a laminated heavy-duty wipe as set forth in claim1, wherein said non-woven fabric is made of high tenacity nylon threadhaving a denier within the range of from about 30 to about 70.

6. A method of forming a laminated heavy-duty wipe as set forth in claim1 wherein said cellulosic tissue has a stretch per ply of between about15% and about 75% and a dry uncreped basis weight within they range ofabout 4 to about 13 pounds per 2,880 square feet.

7. A method of forming a laminated heavy-duty wipe comprising the stepsof providing a web of open-mesh non-woven crossed threads including aset of spaced warp threads extending in the machine direction and a setof ill threads extending in the transverse direction on one side of saidwarp threads and bonded thereto at the crossing points, both the warpthreads and the fill threads being coated with adhesive, laminating alayer of absorbent material formed of two or more plies of cellulosictissue to the warp thread side of said web and bonding said absorbentmaterial to both the warp threads and the lill threads, and laminatingtwo plies of the resulting webtissue laminate together with the layersof tissue on the inside and the fabric web on the outside and bondingthe two tissue layers together to form a composite laminate.

8. A method of forming a laminated heavy-duty wipe as set forth in claim7 wherein a thin applique of fine fibrous material is deposited on thelill thread side of said fabric web and bonded both the warp threads andthe iill threads,I

9.. A method of forming a laminated heavy-duty wipe as set forth inclaim 7 wherein said applique is deposited on said fabric web prior tothe lamination of said layer of absorbent material to said fabric web.

References Cited UNITED STATES PATENTS 2,902,395 1/19-59 Hirschy et al.161--57 3,327,708 6/ 1967 Sokolowski 161-148 3,597,299 8/1971 Thomas etal. 161-129 3,307,992. 3/ 1967 Condon et al. 161-57 WILLIAM A. POWELL,Primary Examiner J. I. BELL, Assistant Examiner U.S. Cl. X.R.

